It was found to regulate breast cancer tumor‐initiating cells through targeting HRAS and HMGA2.14 MiR‐21, one of the most highly expressed miRNAs in breast cancer, has several targets including tropomyosin 1α and programmed cell death 4 (PDCD4).15, 16 It also targets PTEN to promote MCF‐7 breast cancer cell growth.17, 18. Here, PTEN is linked to breast cancer.